Maartje Boer

CROSS-NATIONAL VALIDATION OF THE SMD-SCALE 61 3 to identify countries with particularly high levels of problematic SMU and to inform preventive actions to address the possible detrimental outcomes of problematic SMU (Boer, Stevens, et al., 2020; Boer, Stevens, Finkenauer, De Looze, et al., 2021; Marino et al., 2018b; Piteo & Ward, 2020). Furthermore, international validation of a problematic SMU-scale is crucial for obtaining more robust global knowledge about problematic SMU and identifying the extent to which it imposes a risk to adolescents’ health worldwide. Current Study In response to the lack of cross-national validation of problematic SMU- scales, the present study aimed to investigate the psychometric properties of the SMD-scale using nationally representative cross-national data from the HBSC study. We examined the structural validity, reliability, measurement invariance, and criterion validity of the scale. Thereby, we aim to establish whether the scale is suitable tomeasure and compare adolescent problematic SMU within a broad international context. Methods Sample The HBSC study is a cross-sectional study that has been conducted every four years since 1983 in collaborationwith theWHORegional Office for Europe. The study monitors the health (behaviors) of 11-, 13-, and 15-year-olds. The present study uses the 2017/2018 survey, which includes nationally representative data from 47 countries and regions from the European Region and Canada. More specifically, it includes data from 45 countries and two regional subsamples for Belgium (Flanders and Wallonia). For consistency, we refer to the subsamples as countries. To ensure semantic equivalence across different languages and cultural settings, questionnaires were translated following a standardized protocol (Inchley et al., 2018). National research teams translated the English questionnaire into their national language and back-translated it into English, after which these translations were verified and corrected by language experts from the HBSC network (Inchley et al., 2018; Roberts et al., 2007). All countries strictly followed the samplingmethod and data collection procedures as prescribed by the HBSC international research protocol, which